In various application fields including a semiconductor manufacturing field, multi-function, high quality thin films (for example, high insulation thin films, semiconductor thin films, high dielectric thin films, light-emitting thin films, high magnetic thin films, and super-hard thin films) have been demanded.
For example, in scenes of manufacturing semiconductor apparatuses, semiconductor chips are formed with, for example, a high conductive film having a lower impedance so as to correspond to circuit wiring, a high magnetic film having a circuit wiring and coil function and a magnetic function, a high dielectric film having a circuit capacitor function, and a high insulation film having a high insulation function with less-electrical leakage current.
As conventional technologies for forming these films, for example, thermal Chemical Vapor Deposition (CVD) apparatuses, optical CVD apparatuses, and plasma CVD apparatuses have been used, in particular, a plasma CVD apparatus has often been used. Because a plasma CVD apparatus is superior, than thermal and optical CVD apparatuses, in film formation treatment capability at a lower film formation temperature and at a higher film formation velocity in a shorter period of time, for example.
For example, when a gate insulating film such as a nitride film (SiON, HfSiON, etc.) or an oxide film (SiO2, HfO2) is formed onto a semiconductor substrate, a technology using a plasma CVD apparatus under a reduced pressure atmosphere as described below is widely used.
That is, a gas such as NH3 (ammonia), N2, O2, and O3 (ozone), and a precursor gas (non-heated gas) such as silicon and hafnium are directly supplied into a treatment chamber apparatus in which a CVD treatment will be implemented. In the treatment chamber apparatus, the precursor gas is dissociated through heat or a discharge of electricity to produce metallic particles, and then, through a chemical reaction between the metallic particles and the above described non-heated gas such as NH3 (ammonia) or a radical gas generated using heat or a discharge of electricity, a thin film such as a nitride film or an oxide film is formed onto a treatment-target object.
On the other hand, in a plasma CVD apparatus, high frequency plasma or microwave plasma is directly generated in a treatment chamber apparatus. Therefore, a treatment-target object is exposed to a radical gas or high energy plasma ions (or electrons).
As a prior art document disclosing a technology relating to a plasma CVD apparatus, for example, Patent Document 1 exists.
However, in a film formation treatment performed in a plasma CVD apparatus, as described above, a treatment-target object is directly exposed to plasma. Therefore, the treatment-target object is often damaged by the plasma (ions and electrons), thus a performance of a semiconductor function has been significantly lowered.
On the other hand, in a film formation treatment using a thermal or optical CVD apparatus, a treatment-target object is free from damage by plasma (ions and electrons), and is formed with a high quality nitride film, an oxide film, or another film. However, in the film formation treatment, it is difficult to obtain a high density, large amount radical gas source, and, as a result, a film formation requires an extremely longer period of time.
Recent thermal and optical CVD apparatuses use, as a source gas, a high density NH3 gas or O3 gas that easily dissociates by heat or irradiated light. In addition, in a CVD chamber apparatus, a heating catalyst carrier is provided. Therefore, with the thermal and optical CVD apparatuses, a catalytic action facilitates gas dissociation, thus a nitride film, an oxide film, or another film can be formed in a shorter period of time. However, the shortened period of time is limited, thus significant improvement in film formation has been difficult.
As a apparatus capable of reducing damage to a treatment-target object due to plasma, and further shortening a period of time for film formation, a remote plasma type film formation treatment system exists (for example, see Patent Document 2).
In a technology according to Patent Document 2, a plasma generating area and a treatment-target material treating area are separated by a partition (plasma confinement electrode). Specifically, in the technology according to Patent Document 2, the plasma confinement electrode is provided between a high frequency applying electrode and an opposite electrode to which a treatment-target object is placed. Therefore, in the technology according to Patent Document 2, only neutral active species are supplied onto the treatment-target object.
In addition, in the technology according to Patent Document 3, in a remote plasma source, a source gas is partially activated by plasma. In here, a gas flow channel is surrounded in the remote plasma source. An activated gas generated in the remote plasma source is discharged and supplied toward an apparatus in which a treatment-target object is present.
With the thin film technology described in Patent Document 3, various source gases are used, such as nitrogen, oxygen, ozone, and hydrogen. From the source gas, an activated radical gas is generated, and, by the radical gas, a thin film is formed onto a treatment-target object.
The radical gas is highly reactive. Therefore, by allowing a radical gas at a trace concentration (approximately 1%: 10000 ppm) in maximum to come into contact with a treatment-target object, a chemical reaction is facilitated between metallic particles and the radical gas on the treatment-target object, thus a nitride thin film, an oxide thin film, or a hydrogen bonding thin film can effectively be formed in a short period of time.
A radical gas generating apparatus is provided with a discharge cell to achieve, in the discharge cell, higher electrical field plasma through dielectric barrier discharge becoming atmospheric pressure plasma. Therefore, from the source gas exposed to plasma in the discharge cell, a high quality radical gas is generated and supplied to a CVD apparatus.
In addition, in a CVD apparatus, when a treatment using a gas is to be implemented for a treatment-target object (wafer substrate), the CVD apparatus provided with the treatment-target object is internally heated and decompressed. In the CVD apparatus, an organic metallic compound steam gas (precursor gas) is filled, and, for facilitating oxidation, nitriding, and reduction of metallic particles, an ozone gas, water vapor, a hydrogen gas, or a radical gas (an oxygen radical gas, a nitrogen radical gas, a hydrogen radical gas, or another gas) is supplied. Therefore, in the CVD apparatus, by allowing oxidation substances, nitride substances, and other substances accumulated on the treatment-target object surface to thermally diffuse, a film (formed film) can crystal grow to serve as a function film such as a semiconductor film, an insulating film, or another film on the treatment-target object surface.
Each of various gases (ozone gas, water vapor, hydrogen gas, or radical gas) to be supplied into the CVD apparatus together with a precursor gas as described above is hereinafter referred to as a film formation treatment gas.